UN 2691 — Phosphorus pentabromide
Placard: Corrosive. ERG Guide 137. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
Phosphorus pentabromide is a fuming corrosive solid that reacts with moisture. Water contact can rapidly create heat and toxic corrosive fumes.
Hazard overview: Phosphorus pentabromide is corrosive and water-reactive. Moisture contact can release heat and acid fumes, increasing inhalation and contact hazards.
Response guidance: Keep the product dry, isolate the area and avoid direct water application to the material. Use Dry chemical, dry sand or dry powder; do not use water or foam when compatible, and cool nearby containers only from a safe distance.
Firefighter training notes: Train crews to identify Phosphorus pentabromide by UN number, placard, ERG guide and SDS before choosing entry, isolation or extinguishment tactics.
Regulatory context: Use UN 2691, ERG 137, SDS, container labels and shipping papers to confirm the exact hazard profile and protective action distances.
Storage & handling: Store in closed, compatible containers away from heat, ignition sources and incompatible materials; keep the area ventilated and protected from damage.
UN 2691 Quick Details
Common Hazards of UN 2691
- Corrosive and/or toxic; contact with liquid, solid, vapor or dust can cause severe injury.
- Water or moisture can generate heat and dense corrosive fumes.
- Fire or heating may produce irritating, toxic or corrosive gases.
- Vapors or fumes may collect in low or poorly ventilated areas.
- Runoff from fire control can be corrosive and environmentally damaging.
- Containers may rupture if heated or contaminated with water.
- Contact with incompatible materials may cause violent reaction.
Chemical Identity & Physical Properties
Yellow to reddish-yellow crystalline solid with a pungent irritating odor; fumes in moist air.
| Also known as | PentabromodiphosphorusPhosphoric bromidePBr5 |
| CAS Number | 7789-69-7 |
| Appearance | Yellow to reddish-yellow crystalline solid with a pungent, irritating odor. Fumes in moist air. |
| Flash Point | Not applicable (non-flammable solid) |
| Boiling Point | 106C (223F) decomposes |
| Vapor Density | Not applicable (solid, but evolves dense corrosive fumes) |
| Water Reactivity | Reacts violently with water releasing heat and hydrogen bromide/phosphoric acid fumes |
Fireground Response Guidance — UN 2691
Extinguishing Media
PPE Requirements
Use SCBA with acid-resistant chemical protective suit, gloves, boots and face protection; avoid any direct contact.
Isolation & Evacuation
First Actions for a UN 2691 Incident
- Call 911 and the emergency response number shown on shipping papers or container documents.
- Keep unauthorized personnel away and establish an initial isolation perimeter.
- Stay upwind, uphill and upstream; avoid low areas where vapors or runoff may collect.
- Avoid breathing vapors, dust, smoke or mist and prevent skin and eye contact.
- Keep water away from the product unless specialist guidance confirms it is safe for cooling or vapor control.
- Do not touch damaged containers or spilled material without appropriate chemical PPE.
- Ventilate confined spaces only when personnel are trained, monitored and properly equipped.
- Use ERG guidance, SDS, shipping papers and air monitoring before committing crews.
📋 Copy & Share Field Card
UN 2691 — Phosphorus pentabromideUse for: Quick radio or face-to-face size-up. Short, structured, field-ready.
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
Use for: Quick text to command or incoming units. Fits in a single SMS.